Don't presume too much about the US Navy's fleet decisions. Using that same logic you could presume that smaller, aged and poorly maintained fleets are advantageous for naval supremacy since that appears to be the choice of the US Navy for a couple generations now.

Or you could presume that the complete inability to build a merchant marine fleet was also a strategic advantage!

It's not just the US Navy. It's also the Russian Navy, the French Navy, the Chinese navy of the PLA, the British Navy, the Indian Navy. If nuclear power were cheaper than oil, or anything other than much more expensive, at least one of those would have gone all-nuclear.